Modulation of thalamic network connectivity using transcranial direct current stimulation based on resting-state functional magnetic resonance imaging to improve hypoxia-induced cognitive impairments

Abstract

Hypoxic conditions at high altitudes severely affect cognitive functions such as vigilance, attention, and memory and reduce cognitive ability. Hence, there is a critical need to investigate methods and associated mechanisms for improving the cognitive ability of workers at high altitudes. This study aimed to use transcranial direct current stimulation (tDCS) to modulate thalamic network functional connectivity to enhance cognitive ability. We recruited 20 healthy participants that underwent hypoxia exposure in a hypoxic chamber at atmospheric pressure to simulate a hypoxic environment at 4,000 m. Participants received both sham and real stimulation. tDCS significantly improved the participants’ emotional status, including depression, fatigue, and energy level. These effects were sustained for more than 6 h (P < 0.05 at the second to fifth measurements). In addition, tDCS enhanced vigilance, but this was only effective within 2 h (P < 0.05 at the second and third measurements). Central fatigue was significantly ameliorated, and cerebral blood oxygen saturation was increased within 4 h (P < 0.05 at the second, third, and fourth measurements). Furthermore, functional connectivity results using the thalamus as a seed revealed enhanced connectivity between the thalamus and hippocampus, cingulate gyrus, and amygdala after tDCS. These results indicated that tDCS increased local cerebral blood oxygen saturation and enhanced thalamic network connectivity in a hypoxic environment, thereby improving vigilance, depression, fatigue, and energy levels. These findings suggest that tDCS may partially rescue the cognitive decline caused by hypoxia within a short period. This approach affords a safe and effective cognitive enhancement method for all types of high-altitude workers with a large mental load.

High-altitude cerebral hypoxia promotes mitochondrial dysfunction and apoptosis of mouse neurons

“…A retrospective, cross-sectional study revealed that people living at high altitudes had a higher incidence of depression than those living at low altitudes, suggesting that there was a statistically significant association between high altitude and depressive symptoms ( Zegarra-Rodriguez et al, 2022 ). Additionally, functional magnetic resonance imaging results showed that the emotional changes at high altitudes, including depression, fatigue, and energy levels, were related to connectivity between the limbic system ( Dalong et al, 2022 ). In this study, the open field test and elevated plus maze also found that mice in HAH group showed anxiety-like behavior.…”

Mechanism, prevention and treatment of cognitive impairment caused by high altitude exposure

“…( Nelson et al, 2014 ; Douglas et al, 2015 ). In recent years, some reports showed that TDCS can increase local cerebral oxygen saturation, improve fatigue, enhance energy, and improve some plateau brain cognitive ability and plateau mental work ability to a certain extent ( Dalong et al, 2022 ).…”